Light source unit and projector

ABSTRACT

There is provided a light source unit comprising an excitation light shining device for emitting excitation light, a luminescent plate having a luminescent light emitting area on a base material and adapted to emit a luminescent light of a predetermined wavelength band by excitation light from the excitation shining device, two types of light source devices for emitting light of wavelength bands different from that of the light from the luminescent plate, a light guiding optical system for guiding the light from the luminescent plate and the rays from the light sources to a predetermined plane, and a light source control device for controlling the emission from the excitation light shining device and the light sources, wherein a synthetic light or a single-color light are emitted by controlling the emissions from the excitation light shining device and the light sources by the light source control device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority under35 USC 119 of Japanese Patent Application No. 2009-247689 filed on Oct.28, 2009, the entire disclosure of which, including the description,claims, drawings and abstract thereof, is incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a light source unit and a projectorwhich includes the light source unit.

2. Description of the Related Art

Patent Document 1 (Japanese Unexamined Patent Publication No.2004-3411505), for example, proposes a light source unit having a lightemitting diode which functions as an excitation light source and aluminescent wheel in which luminescent material layers are formed on atransparent base material for converting ultraviolet light emitted fromthe excitation light source into visible light.

The proposal made in Patent Document 1 is a configuration in which lightrays of red, green and blue wavelength bands can be emitted sequentiallyby rotating the luminescent wheel. This requires excitation light to beshone continuously onto red, green and blue luminescent light emittingareas on a surface of the luminescent wheel, which requires, in turn,the excitation light source to be driven at all times, leading to aproblem that the life of the excitation light source is shortened due toheat generated therein as a result of the continuous driving thereof. Tocope with this problem, the driving output of the excitation lightsource needs to be suppressed so as to suppress, in turn, an increase intemperature of the excitation light source. In addition, due to theconfiguration in which the red, green and blue luminescent light raysare emitted sequentially from the corresponding luminescent lightemitting areas which are formed on the luminescent wheel, it is notpossible to enhance the luminance of an image by producing white lightor light of a wavelength band of a highly pure complementary colorthrough combination of the light rays of the respective colors. Further,in this proposal, since the red, green and blue light rays emitted fromthe corresponding luminescent light emitting areas are controlled withtime sharing, the rotation of a wheel motor needs to be controlled.

Since the luminous efficiency of red, green and blue light rays whichare emitted from the corresponding luminescent light emitting areaslargely depends on the physical properties of the luminescent materialsused, there is caused a problem that it is difficult to display on ascreen an image which is superior in color balance.

It is also possible to propose a light source unit which has a pluralityof types of semiconductor light emitting devices so that red, green andblue light rays can be produced by corresponding light emitting diodes.In the case of this configuration being adopted, however, the luminousefficiency of a green semiconductor light emitting device is lower thanthose of red and blue semiconductor light emitting devices, leading to aproblem that it is difficult to obtain light source light with a highluminance.

SUMMARY OF THE INVENTION

The invention has been made in view of the problems inherent in therelated art and provides a light source unit having two types of lightsource devices each having a semiconductor light emitting device such asa light emitting diode, a luminescent plate having a luminescentmaterial layer for producing a light ray of a predetermined wavelengthband by receiving excitation light, and an excitation light shiningdevice for shining excitation light onto a luminescent material on theluminescent plate. Then, the light source unit is configured so as toemit light rays of predetermined colors by use of a luminescent lightray emitted from the luminescent plate onto which excitation light isshone by the excitation light source device and light source light rayswhich are emitted from the two types of light source devices,respectively. An object of the invention is to provided a light sourceunit which can realize an increase in luminance through emission of notonly a single-color light ray but also a synthetic light ray bycontrolling individually the emission of light from the excitation lightshining device and the two types of light source devices and a projectorincluding this light source unit.

With a view to attaining the object, according to a first aspect of theinvention, there is provided a light source unit comprising:

an excitation light shining device for emitting excitation light;

a luminescent plate having a luminescent light emitting area in which aluminescent material is laid on a base material and adapted to emit aluminescent light ray of a predetermined wavelength band by excitationlight being shone onto the luminescent light emitting area from theexcitation shining device;

two types of light source devices for emitting light rays of wavelengthbands which are different from that of the luminescent light ray emittedfrom the luminescent plate;

a light guiding optical system for guiding individually the luminescentlight ray emitted from the luminescent plate and the light rays emittedfrom the two types of light sources to a predetermined plane; and

a light source control device for controlling individually the emissionof light from the excitation light shining device and the two types oflight sources, wherein

a synthetic light ray or a single-color light ray are emitted bycontrolling individually the emission of light from the excitation lightshining device and the two types of light sources by the light sourcecontrol device.

With a view to attaining the object, according to a second aspect of theinvention, there is provided a projector comprising the light sourceunit set forth in the first aspect of the invention, a display device, alight source-side optical system for guiding the light ray from thelight source unit to the display device, a projection-side opticalsystem for projecting an image emitted from the display device onto ascreen, and a projector control device for controlling the light sourceunit and the display device.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be understood much sufficiently by reading thefollowing detailed description thereof and referring to accompanyingdrawings. However, the detailed description and the accompanyingdrawings are intended mainly to describe the invention and are notintended to limit the scope thereof. In the accompanying drawings;

FIG. 1 is a perspective view showing an external appearance of aprojector including a light source unit according to an embodiment ofthe invention,

FIG. 2 is a functional circuit block diagram of the projector includingthe light source unit according to the embodiment of the invention,

FIG. 3 is an exemplary plan view showing an internal construction of theprojector including the light source unit according to the embodiment ofthe invention,

FIG. 4A is an exemplary front view of a luminescent wheel according tothe embodiment of the invention, and FIG. 4B is an exemplary partiallysectional plan view of the luminescent wheel according to the embodimentof the invention,

FIG. 5 is a time chart showing periods of time when an excitation lightshining device and two types of light source devices according to theembodiment of the invention are turned on,

FIGS. 6A and 6B are time charts showing periods of time when theexcitation light shining device and the two types of light sourcesaccording to the embodiment of the invention are turned on, and

FIGS. 7A and 7B are time charts showing periods of time when theexcitation light shining device and the two types of light sourcesaccording to the embodiment of the invention are turned on.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, a mode for carrying out the embodiment will be described. Aprojector 10 includes a light source unit 60, a display device 51, anlight source-side optical system 170 for guiding light from the lightsource unit 60 to the display device 51, a projection-side opticalsystem 220 for projecting an image emitted from the display device 51onto a screen, and a projector control device for controlling the lightsource unit 60 and the display device 51.

The light source unit 60 further includes an excitation light shiningdevice 70, a luminescent light emitting device 100 having a luminescentwheel 101 which is controlled to be driven to rotate, a red light sourcedevice 120, a blue light source device 300, and a light guiding opticalsystem 140. The excitation light shining device 70 includes anexcitation light source 71 for shining excitation light of a bluewavelength band onto the luminescent wheel 101. The luminescent wheel101 of the luminescent light emitting device 100 has an annularluminescent light emitting area where a green luminescent material layer103 is laid on a circular disc-like metallic base material. In addition,a reflecting surface which reflects light is formed on a boundary planeof the metallic base material in the luminescent light emitting area,and the green luminescent material layer 103 which receives theexcitation light to emit light of a green wavelength band is formed onthe reflecting surface.

Consequently, when the light of the blue wavelength band is shone ontothe luminescent light emitting area from the excitation light shiningdevice 70, the light of the green wavelength band is emitted from thegreen luminescent material layer 103 which has absorbed the blue lightas excitation light. Namely, the luminescent wheel 101 is made up of themetallic base material which is driven to rotate by a wheel motor 110and functions as a luminescent plate which emits the luminescent lightof the green wavelength band by receiving the excitation light on theannular luminescent light emitting area which is formed on the basematerial.

The red light source device 120 has a red light source 121 which is asemiconductor light emitting device for emitting light of a redwavelength band. The blue light source device 300 has a blue lightsource 301 which is a semiconductor light emitting device for emittinglight of a blue wavelength band. The light guiding optical system 140includes pluralities of dichroic mirrors and collective lenses which aredisposed in predetermined positions so as to alter optical axes of thelight rays of the various colors which are emitted from the luminescentwheel 101, the red light source device 120 and the blue light sourcedevice 300 to thereby collect the colored light rays to an incident portof a light tunnel 175 which constitutes a predetermined plane.

In addition, the light source unit 60 can emit synthetic light orsingle-color light by controlling individually the emission of lightfrom the excitation light shining device 70, the red light source device120 and the blue light source device 300 so that they can be illuminatedor turned on individually by a light source control device of theprojector control device. Specifically, the light source control deviceis configured so as to effect a control to turn on individually theexcitation light shining device 70, the red light source device 120 andthe blue light source device 300 in corresponding periods of time whenlight rays of red, green and blue wavelength bands are emittedindividually and a control to turn on all of the excitation lightshining device 70, the red light source device 120 and the blue lightsource device 300 in a period of time when light of a white wavelengthband is emitted by combining the light rays of red, green and bluewavelength bands.

By adopting this configuration, the light source unit 60 is allowed toemit sequentially the light rays of red, white, green and bluewavelength bands. Then, a highly bright color image can be produced on ascreen by a DMD, which is the display device 51 of the projector 10,displaying, with time sharing, the light rays of the respective colorsin accordance with data.

Hereinafter, an embodiment of the invention will be described in detailby reference to the accompanying drawings. FIG. 1 is a perspective viewshowing an external appearance of a projector 10. In this embodiment,left and right with respect to the projector 10 denote, respectively,left and right directions with respect to a projecting direction. Inaddition, front and rear denote, respectively, front and rear directionswith respect to a direction towards a screen side of the projector 10and a traveling direction of a pencil of light or light rays.

As is shown in FIG. 1, the projector 10 has a substantially rectangularparallelepiped shape and has a lens cover 19 which covers a projectionport which is laid to a side of a front panel 12 which is referred to asa front side panel of a housing of the projector, as well as a pluralityof outside air inlet ports 18 in the front panel 12. Further, althoughnot shown, the projector 10 includes an Ir reception part for receivinga control signal from a remote controller.

In addition, a keys/indicators part 37 is provided on an upper sidepanel 11 of the housing. Disposed on this keys/indicators part 37 arekeys and indicators which include a power supply switch key, a powerindicator which informs whether the power supply is on or off, aprojection switch key which switches on or off projection, an overheatindicator which informs of an overheat condition when the light sourceunit, the display device or the control circuit overheats and the like.

Further, provided on a back side or a back side panel of the housing arean input/output connectors part where USB terminals, an image signalinput D-SUB terminal, an S terminal, an RCA terminal and the like andvarious types of terminals 20 including a power supply adaptor plug andthe like. A plurality of outside air inlet ports 18 are formed in theback side panel. A plurality of inside air outlet ports 17 are formed ineach of a right-hand side panel 14 which constitutes a side panel of thehousing, not shown, and a left-hand side panel 15 which constitutes aside panel shown in FIG. 1. In addition, outside air inlet ports 18 arealso formed in a corner portion of the left-hand side panel 15 whichlies in proximity to the back side panel. Further, a plurality ofoutside air inlet ports or a plurality of inside air outlet ports areformed in a bottom panel, which is not shown, in each of positions lyingin proximity to the front side panel, the back side panel, the left-handside panel and the right-hand side panel.

Next, a projector control device of the projector 10 will be describedby use of a block diagram in FIG. 2. The projector control deviceincludes a control unit 38, an input/output interface 22, an imagetransforming part 23, a display encoder 24, a display drive part 26 andthe like. In addition, image signals of various standards that areinputted from the input/output connector part 21 are sent via theinput/output interface 22 and a system bus (SB) to the imagetransforming part 23 where the image signals are transformed so as to beunified into an image signal of a predetermined format which is suitablefor display. Thereafter, the image signals so transformed are outputtedto the display encoder 24.

The control unit 38 governs the control of respective operations ofcircuitries within the projector 10. The control unit 38 is made up of aCPU, a ROM which stores in a fixed fashion operation programs of varioustypes of settings and a RAM which is used as a work memory.

In addition, the display encoder 24 deploys the image signals enteredthereinto on a video RAM 25 for storage therein and generates a videosignal from the contents stored in the video RAM 25, outputting thevideo signal so generated to the display drive part 26.

The display drive part 26 functions as a display device controller anddrives a display device 51 which is a spatial optical modulator (SOM) bycontrolling a frame rate as required in accordance with an image signaloutputted from the display encoder 24. A pencil of light or light rayswhich are emitted from a light source unit 60 in accordance with thecontrol of the display device 51 are shone onto the display device 51via a light source-side optical system to thereby form an optical imageby reflected light reflected at the display device 51. Further, theimage so formed is projected on to a screen, not shown, for display viaa projection-side optical system, which will be described later. Amovable lens group 235 of the projection-side optical system is drivenby a lens motor 45 for zooming or focusing.

In addition, an image compression/expansion part 31 performs a recordingoperation in which a luminance signal and a color difference signal ofan image signal are data compressed through ADCT and Huffman effect andthe compressed data is sequentially written on a memory card 32 which isconfigured as a detachable recording medium. The imagecompression/expansion part 31 further performs an operation in whichwhen in a reproducing mode, the image compression/expansion part 31reads out image data recorded on the memory card 32 and expandsindividual image data which make up a series of dynamic images frame byframe. Then, the image data so expanded is outputted to the displayencoder 24 via the image transforming part 23 so as to enable thedisplay of dynamic images on the basis of the image data stored on thememory card 32.

Operation signals generated at the keys/indicators part 37 which is madeup of the main keys and indicators provided on the upper side panel 11of the housing are sent out directly to the control unit 38, while keyoperation signals generated by operating keys on the remote controllerare received by the Ir reception part 35, and a code signal demodulatedat an Ir processing part 36 is outputted to the control part 38.

In addition, an audio processing part 47 is connected to the controlpart 38 via the system bus (SB). This audio processing part 47 includesa sound source circuit such as a PCM sound source. When in a projectionmode and reproducing mode, the audio processing part 47 converts audiodata into analog signals and drives a speaker 48 to output loudly soundor voice based on the audio data.

Additionally, the control unit 38 controls a light source controlcircuit 41 which is configured as a light source control device. Thislight source control circuit 41 controls individually the emission oflight by an excitation light shining device, a red light source deviceand a blue light source device of the light source unit 60 so that theyare turned on individually or altogether so as to allow the light sourceunit 60 to emit light of a predetermined wavelength band which isrequired at the time of generating an image.

Further, the control unit 38 causes a cooling fan drive control circuit43 to detect temperatures through a plurality of sensors which areprovided at the light source unit 60 so as to control the rotating speedof a cooling fan based on the results of the temperature detection. Inaddition, the control unit 38 also causes the cooling fan drive controlcircuit 43 to make the cooling fan continue to rotate even after thepower supply of a projector main body is switched off by use of a timeror the like or to make the power supply to the projector main body becut off depending upon the results of the temperature detection by thetemperature sensors.

Next, an internal construction of the projector 10 will be described.FIG. 3 is an exemplary plan view showing an internal construction of theprojector 10. As is shown in FIG. 3, the projector 10 includes a controlcircuit board 241 which is disposed in proximity to the right-hand sidepanel 14. This control circuit board 241 includes a power supply circuitblock and a light source control block. In addition, the projector 10includes the light source unit 60 which is provided at a substantiallycentral portion of the housing of the projector. Further, the projector10 includes an optical system unit 160 which is disposed between thelight source unit 60 and the left-hand side panel 15.

The light source unit 60 is disposed at a substantially central portionin a left-right direction of the housing of the projector. A luminescentlight emitting device 100 which is disposed in proximity to the frontpanel 12 is disposed on optical axes of light rays which are emittedfrom an excitation light shining device 70 which is disposed inproximity to the back panel 13. In addition, the luminescent lightemitting device 100 is disposed so that optical axes of light rays whichare emitted therefrom become parallel to a blue light source device 300which is disposed in proximity to the front panel 12. The light sourceunit 60 includes further a red light source device 120 which is disposedbetween the excitation light shining device 70 and the luminescent lightemitting device 100, and a light guiding optical system 140 which guidesthe optical axes of the light rays emitted from the luminescent lightemitting device 100, optical axes of the light rays emitted from the redlight source device 120 and optical axes of the light rays emitted fromthe blue light source device 300 so that the respective optical axes ofthe light rays converge to the same optical axis so as to be collectedto an incident opening of a light tunnel 175 which constitutes apredetermined plane.

The excitation light shining device 70 includes an excitation lightsource 71 which is disposed so that optical axes of light rays emittedtherefrom become parallel to the back panel 13, a reflecting mirrorgroup 75 which alters the optical axes of the light lays emitted fromthe excitation light source 71 through 90 degrees so as to be orientedtowards the front panel 12, a collective lens 78 for collecting thelight rays emitted from the excitation light source 71 and reflected onthe reflecting mirror group 75 and a heat sink 81 which is disposedbetween the excitation light source 71 and the right-hand side panel 14.

The excitation light source 71 includes a plurality of blue laser diodeswhich are arranged into a matrix configuration. In addition, collimatorlenses 73 are disposed individually on optical axes of the blue laserdiodes so as to convert light rays emitted from the respective bluelaser diodes into parallel light rays. In the reflecting mirror group75, a plurality of reflecting mirrors are arranged in a step-likefashion so as to emit the light rays emitted from the excitation lightsource 71 towards the collective lens 78 while reducing sectional areasof the light rays so emitted in one direction.

A cooling fan 261 is disposed between the heat sink 81 and the backpanel 13. The excitation light source 71 is cooled by the cooling fan261 and the heat sink 81. Further, a cooling fan 261 is disposed betweenthe reflecting mirror group 75 and the back panel 13, so that thereflecting mirror group 75 and the collective lens 78 are cooled by thecooling fan 261.

The luminescent light emitting device 100 includes a luminescent wheel101 which is disposed so as to be at right angles to the optical axis ofthe light emitted from the excitation light shining device 70, a wheelmotor 110 which drives the luminescent wheel 101 to rotate and acollective lens group 111 which collects light rays emitted from theluminescent wheel 101 in the direction of the back panel 13.

As is shown in FIG. 4, the luminescent wheel 101 includes an annularluminescent light emitting area which is formed in a recess portionformed in a circumferential direction in a circular disc-shaped metallicbase material. The annular luminescent light emitting area receives thelight emitted from the excitation light source 71 as excitation light toemit luminescent light of a green wavelength band. Namely, theluminescent wheel 101 functions as a luminescent plate which receivesexcitation light so as to emit luminescent light. A surface of therecess portion formed in the circumferential direction of the circulardisc-shaped metallic base material is mirror finished through silvervapor deposition so as to form a reflecting surface thereon whichreflects light, and a green luminescent material layer 103 is laid onthis reflecting surface.

The light emitted from the excitation light shining device 70 so as tobe shone onto the green luminescent material layer 103 of theluminescent wheel 101 excites a green luminescent material in the greenluminescent material layer 103. Luminescent light rays which are emittedby luminescence in every direction from the green luminescent materialare emitted directly towards the excitation light source 71 side or isreflected on the reflecting surface of the luminescent wheel 101 so asto be then emitted towards the excitation light source 71 side.Excitation light which is shone onto the metallic base material withoutbeing absorbed by the luminescent material in the luminescent materiallayer 103 is reflected on the reflecting surface so as to enter theluminescent material layer 103 again to excite the luminescent materiallayer 103. Consequently, by making the surface of the recess portion inthe luminescent wheel 101 function as the reflecting surface, theutilization efficiency of excitation light emitted from the excitationlight source 71 can be increased so that the luminescent wheel 101 canluminesce more brightly.

In excitation light which is reflected towards the luminescent materiallayer 103 side on the reflecting surface of the luminescent wheel 101,excitation light emitted towards the excitation light source 71 sidewithout being absorbed by the luminescent material passes through aprimary dichroic mirror 141, which will be described later, and returnsin the direction of the excitation light shining device 70. Thus, thereis no such situation that excitation light is emitted to the outside ofthe light source unit 60. The luminescent light is reflected by theprimary dichroic mirror 141. Then, as is shown in FIG. 3, a cooling fan261 is disposed between the well motor 110 and the front panel 12,whereby the luminescent wheel 101 is cooled by this cooling fan 261.

The red light source device 120 includes a red light source 121 which isdisposed so that its optical axis becomes parallel to the excitationlight source 71 and a collective lens group 125 which collects lightemitted from the red light source 121. This red light source device 120is disposed so that its optical axis intersects the light emitted fromthe excitation shining device 70 and the luminescent light of the greenwavelength band emitted from the luminesce wheel 101 at right angles.The red light source 121 is a red light emitting diode which is asemiconductor light emitting device which emits light of a redwavelength band. The red light source device 120 includes further a heatsink 130 which is disposed on a side of the red light source 121 whichfaces the right-hand side panel 14. A cooling fan 261 is disposedbetween the heat sink 130 and the front panel 12, whereby the red lightsource 121 is cooled by this cooling fan 261.

The blue light source device 300 includes a blue light source 301 whichis disposed so as to be parallel to the optical axis of the luminescentlight emitted from the luminescent light emitting device 100 and acollective lens group 305 which collects light emitted from the bluelight source 301. This blue light source device 300 is disposed so thatits optical axis intersects the light emitted from the red light sourcedevice 120. The light source 301 is a blue light emitting diode which isa semiconductor light emitting device which emits light of a bluewavelength band. The blue light source device 300 includes further aheat sink 310 which is disposed on a side of the blue light source 301which faces the front panel 12. A cooling fan 261 is disposed betweenthe heat sink 310 and the front panel 12, whereby the blue light source301 is cooled by this cooling fan 261.

The light guiding optical system 140 includes a collective lens whichcollects light rays of red, green and blue wavelength bands and dichroicmirrors which alter optical axes of the light rays of the respectivewavelength bands so that the light rays converge to the same opticalaxis. Specifically, the primary dichroic mirror 141 is disposed in aposition where the optical axes of the light of the blue wavelength bandemitted from the excitation light shining device 70 and the light of thegreen wavelength band emitted from the luminescent wheel 101 intersectthe optical axis of the light of the red wavelength band emitted fromthe red light source device 120. This primary dichroic mirror 140transmits the light of the blue wavelength band and the light of the redwavelength band and reflects the light of the green wavelength band soas to alter the optical axis of the light of the green wavelength bandthrough 90 degrees in the direction of the left-hand side panel 15.

A secondary dichroic mirror 148 is disposed in a position where theoptical axis of the light of the blue wavelength band emitted from theblue light source device 300 and the optical axis of the light of thered wavelength band emitted from the red light source device 120intersect each other. This secondary dichroic mirror 148 transmits thelight of the blue wavelength band and reflects the light of the greenwavelength band and the light of the red wavelength band so as to alterthe optical axes of the light of the green wavelength band and the lightof the red wavelength band through 90 degrees in the direction of theback panel 13. A collective lens is disposed between the primarydichroic mirror 141 and the secondary dichroic mirror 148.

The optical system unit 160 has a substantially U-shape and includesthree blocks such as an illumination-side block 161 which is positionedto a left-hand side of the excitation light shining device 70, an imagegeneration block 165 which is positioned in proximity to a positionwhere the back panel 13 and the left-hand side panel 15 intersect eachother, and a projection-side block 168 which is positioned between thelight guiding optical system 140 and the left-hand side panel 15.

The illumination-side block 161 includes part of a light source-sideoptical system 170 which guides light source light emitted from thelight source unit 60 to the display device 51 which is included in theimage generation block 165. The light source-side optical system 170that is included in the illumination-side block 161 has the light tunnel175 which converts light rays emitted from the light source unit 60 intolight rays whose intensity distribution is uniform, a collective lens173 which collects the light source light onto an incident plane of thelight tunnel 175, a collective lens 178 which collets light rays emittedfrom the light tunnel 175, an optical axis altering mirror 181 whichalters optical axes of the light rays emitted from the light tunnel 175in the direction of the image generation block 165 and the like.

The image generating block 165 has, as the light guiding optical system170, a collective lens 183 which collects the light source light whichis reflected by the optical axis altering mirror 181 to the displaydevice 51 and a shining mirror 185 which shines the light rays whichhave passed through the collective lens 183 onto the display device 51at a predetermined angle. The image generation block 165 includesfurther a DMD which is the display device 51. A heat sink 190 isdisposed between the display device 51 and the back panel 13 so as tocool the display device 51. The display device 51 is cooled by this heatsink 190. A collective lens 195, which constitutes the projection-sideoptical system 220, is disposed in proximity to a front of the displaydevice 51.

The projection-side block 168 has a lens group of the projection-sideoptical system 220 which projects on-light reflected by the displaydevice 51 onto the screen. The projection-side optical system 220 isconfigured as a variable focus lens including a fixed lens group 225which is incorporated in a fixed lens barrel and a movable lens group235 which is incorporated in a movable lens barrel, whereby the variablefocus lens enables zooming and focusing operations by moving the movablelens group 235 by a lens motor.

Next, the control of the excitation light shining device 70, the redlight source device 120 and the blue light source device 300 by thelight source control device will be described. The light source controldevice controls, with time sharing, turning on and off operations of theexcitation light shining device 70, the red light source device 120 andthe blue light source device 300 individually. By adopting thisconfiguration, the light source unit 60 can emit synthetic light orsingle-color light.

Specifically, as is shown in FIG. 5, the light source control device isconfigured so as to execute a control to turn on the red light sourcedevice 120, the excitation light shining device 70 and the blue lightsource device 300 individually and sequentially within one frame so asto include periods of time when the light of the red wavelength band,the light of the green wavelength band and the light of the bluewavelength band are emitted individually.

By doing so, when only the red light source device 120 is turned on, redlight is incident on the light tunnel 175 via the light guiding opticalsystem 140. When only the excitation light shining device 70 is turnedon, excitation light is shone onto the luminescent wheel 101 of theluminescent light emitting device 100, whereby green light emitted fromthe luminescent wheel 101 is incident on the light tunnel 175 via thelight guiding optical system 140. When only the blue light source device300 is turned on, blue light is incident on the light tunnel 175 via thelight guiding optical system 140. Namely, the light source unit 60 canemit sequentially light rays of the respective colors (red, green, blue)by turning on the excitation light shining device 70 and the two typesof light source devices 120, 300 individually and separately to emitcorresponding light rays. Then the DMD, which is the display device 51of the projector 10, displays with time sharing the red, green and bluelight rays in accordance with data, thereby making it possible togenerate a color image on the screen.

Since the light source control device can control the emission of lightby the excitation light shining device 70 and the two types of lightsource devices 120, 300 individually, a control can be effected to turnon any two or all of the three light source devices of the excitationlight shining device 70 and the two types of light source devices 120,300. Namely, as is shown in FIG. 6A, the light source control device isconfigured so as to effect a control to turn on the red light sourcedevice 120, the excitation light shining device 70 and the blue lightsource device 300 altogether so as to include a period of time whenlight of a white wavelength band is emitted which is generated bycombining the light rays of the red, green and blue wavelength bands.Further, as is shown in FIG. 6B, the light source control device is alsoconfigured to effect a control to turn on the red light source device120 and the excitation light shining device 70 so that the period oftime when the red light source device 120 is turned on overlaps theperiod of time when the excitation light shining device 70 is turned onby causing the excitation light shining device 70 to start to be turnedon while the red light source device 120 is being turned on.

By adopting this configuration, the light source unit 60 can emit notonly the single-color light rays of red, green and blue wavelength bandsbut also a light ray of a white wavelength band which is a syntheticlight ray. Namely, the light source unit 60 can emit sequentially thelight rays of red, white, green and blue wavelength bands. In addition,the light source unit 60 can generate and emit a light ray of a yellowwavelength band which is a synthetic light ray of the red and greenlight rays. Namely, the light source unit 60 can also emit sequentiallythe light rays of red, yellow, green and blue wavelength bands.Consequently, a highly bright color image can be generated on the screenby displaying with time sharing, the light rays of the respective colorsin accordance with data by the DMD, which is the display device 51 ofthe projector 10.

In addition, as is shown in FIG. 7A, the light source control device isconfigured so as to effect a control to turn on the red light sourcedevice 120, the excitation light shining device 70 and the blue lightsource device 300 separately and sequentially at a double speed withinone frame so as to include periods of time when the light rays of red,green and blue wavelength bands are emitted separately.

By adopting this configuration, when only the red light source device120 is turned on, the red light is incident on the light tunnel 175 viathe light guiding optical system 140. In addition, when only theexcitation light shining device 70 is turned on, the green light emittedfrom the luminescent wheel 101 by the excitation light being shone ontothe luminescent wheel 101 of the luminescent light emitting device 100is incident on the light tunnel 175 via the light guiding optical system140. Additionally, when only the blue light source device 300 is turnedon, the blue light is incident on the light tunnel 175 via the lightguiding optical system 140. The red light source device 120, theexcitation light shining device 70 and the blue light source device 300are separately turned on to emit the corresponding light rays at thedouble speed within one frame. Namely, the light source unit 60 can emitthe single-color light rays of the respective colors (red, green andblue) sequentially at the double speed by causing the excitation lightshining device 70 and the two types of light source devices 120, 300 tobe turned on separately. Consequently, a color image in which a colorregistration error is made difficult to occur can be generated on thescreen by displaying, with time sharing, the light rays of therespective colors at the double speed in accordance with data by theDMD, which is the display device 51 of the projector 10.

Further, as is shown in FIG. 7B, the light source control device isconfigured so as to effect a control to turn on the red light sourcedevice 120, the excitation light shining device 70 and the blue lightsource device 300 separately at a triple speed within one frame so as toinclude periods of time when the light rays of red, green and bluewavelength bands are emitted separately.

By adopting this configuration, when only the red light source device120 is turned on, the red light is incident on the light tunnel 175 viathe light guiding optical system 140. In addition, when only theexcitation light shining device 70 is turned on, the green light emittedfrom the luminescent wheel 101 by the excitation light being shone ontothe luminescent wheel 101 of the luminescent light emitting device 100is incident on the light tunnel 175 via the light guiding optical system140. Additionally, when only the blue light source device 300 is turnedon, the blue light is incident on the light tunnel 175 via the lightguiding optical system 140. The red light source device 120, theexcitation light shining device 70 and the blue light source device 300are separately turned on to emit the corresponding light rays at thetriple speed within one frame. Namely, the light source unit 60 can emitthe single-color light rays of the respective colors (red, green andblue) sequentially at the triple speed by causing the excitation lightshining device 70 and the two types of light source devices 120, 300 tobe turned on separately. Consequently, a color image in which a colorregistration error is made difficult to occur can be generated on thescreen by displaying, with time sharing, the light rays of therespective colors at the triple speed in accordance with data by theDMD, which is the display device 51 of the projector 10.

Namely, according to the invention, there can be provided the lightsource unit 60 which can emit the highly bright light rays of therespective colors (red, green and blue) by including the red lightsource device 120 and the blue light source device 300 which have thesemiconductor light emitting devices such as light emitting diodes andthe luminescent light emitting device which emits the green luminescentlight by the luminescent material being excited by the excitation lightemitted from the excitation light shining device 70, and the projector10 which can project an image which is superior in color balance ontothe screen by including the light source unit 60.

In addition, there can be provided the light source unit 60 which canrealize an increase in luminance by emitting not only the single-colorlight rays but also the synthetic light ray of yellow or whitewavelength band by controlling individually the emission of light fromthe excitation light shining device 70 and the two types of light sourcedevices by the light source control device based on the configuration inwhich the light rays of the respective colors (red, green and blue) canbe emitted by the luminescent light emitting device 100 onto which theexcitation light is shone by the excitation light shining device 70 andthe two types of light source devices 120, 300, and the projector 10including this light source unit.

Further, there can be provided the light source unit 60 which cangenerate a color image in which a color registration error is madedifficult to occur by controlling the emission of light from theexcitation light shining device 70 and the two types of light sourcedevices at the double or triple speed within one frame based on theconfiguration in which the light rays of the respective colors (red,green and blue) can be emitted by the luminescent light emitting device100 onto which the excitation light is shone by the excitation lightshining device 70 and the two types of light source devices 120, 300,and the projector 10 including this light source unit.

In addition, the light source unit 60 can also generate a light ray of awavelength of magenta by causing both the red light source device 120and the blue light source device 300 to be turned on together, as wellas a light ray of a wavelength of cyan by causing both the excitationlight shining device 70 and the blue light source device 300 to beturned on together. Namely, the light source unit 60 can not only alterfreely a ratio of the periods of time when the light rays of wavelengthbands of primary colors (red, green and blue) are turned on but alsocombine freely any two of or all the three of the periods of time whenthe light rays of wavelength bands of primary colors (red, green andblue) are turned on to emit the light ray of the wavelength band of anyof the complementary colors (yellow, cyan and magenta) or the light rayof the wavelength band of white.

The light source control device can control the luminance of an image tobe produced freely by controlling the illumination time of theexcitation light shining device 70 and the two types of light sourcedevices 120, 300 so that the emission time of each colored light ray isshortened. The light source control device can also control the tint orbrightness of an image to be produced based on a configuration in whichthe light source control device controls either of the excitation lightshining device 70 and the two types of light source devices 120, 300 soas to suppress the out put of the light source in question.Consequently, there can be provided the projector 10 which can projectimages which match various conditions onto the screen by generating suchimages by executing a mode having a variety of brightnesses, controllingthe tint, increasing the luminance of an image or suppressing theoccurrence of color registration error therein.

According to the invention, since the emission of light from theexcitation light shining device 70 and the two types of light sourcedevices 120, 300 can be controlled individually, the rotation of theluminescent wheel 101 having the luminescent light emitting area doesnot have to be controlled. By adopting this configuration, the rotationof the luminescent wheel 101 can be driven to rotate by the wheel motor110 whose construction is simple without providing a rotating positiondetection device. Thus, a reduction in costs incurred for fabrication ofthe light source unit 60 and the projector 10 can be realized.

Since the duty drive of the excitation light source 71, the red lightsource 121 and the blue light source 301 is enabled or thenon-illumination time of the excitation light source 71, the red lightsource 121 and the blue light source 301 can be lengthened, thetemperature of the light source unit 60 can be maintained low. Inaddition, since the mean current value is lowered, there can be providedthe light source unit 60 which can generate bright light rays of therespective colors (red, green and blue) by increasing the output whenthe excitation light source 71, the red light source 121 and the bluelight source 301 are turned on to emit light by increasing the impressedvoltage and the projector 10 which includes the light source unit 60.

Since a surface area of the luminescent light emitting area where theexcitation light is received can be expanded by driving to rotate theluminescent wheel 101 by the wheel motor 110, an increase in temperatureof the luminescent material can be suppressed, thereby making itpossible not only to increase the luminous efficiency of the luminescentmaterial but also prevent the deterioration thereof. By doing so, therecan be provided the light source unit 60 which can maintain itsperformance over a long period of time and the projector 10 whichincludes the light source unit 60.

The invention is not limited to the embodiment that has been describedheretofore but can be modified or improved freely without departing fromthe spirit and scope of the invention. For example, the light sourcecontrol device is not provided in the projector 10 but may be providedseparately in the light source unit 60. In addition, the layout of therespective optical systems is not limited to that described in theembodiment but may be configured variously. Further, the luminescentwheel 101 does not have to be configured so as to be rotated by thewheel motor 110 but may be fixedly disposed as a rectangular luminescentplate, thereby making it possible to omit the wheel motor 110. Thisenables a further reduction in costs incurred for fabrication of thelight source unit 60 and the projector 10.

In the event that the luminescent plate is fixed, a controlling devicefor altering the shining direction of light from the excitation lightshining device 70 is provided between the excitation light shiningdevice 70 and the luminescent plate. Alternatively, a light sourcedriving device is provided for driving the excitation light shiningdevice 70 so as to alter the position and/or the light shining directionthereof. By doing so, the position of a shining spot of light from theexcitation light shining device 70 is shifted within the luminescentlight emitting area so as to expand a surface area of the light shiningarea, thereby making it possible to avoid the concentration of heat. Inaddition, as the controlling device, a polariscope can be adopted whichutilizes a KTN crystal, an acoustic optical device, an MEMS mirror orthe like.

In the embodiment, while the dichroic mirrors are used to alter thedirections of the optical axes and to select transmission or reflectionin accordance with wavelengths, the invention is not limited thereto.For example, other alternative devices such as dichroic prisms may beused to replace the dichroic mirrors.

In the embodiment, while the light source unit 60 is made up of theexcitation light shining device 70 and the two types of light sourcedevices such as the red light source device 120 and the blue lightsource device 300, the invention is not limited thereto. A configurationmay be adopted in which light source devices can additionally beprovided which emit light rays of wavelength bands of complementarycolors such as yellow and cyan. The excitation light source 71 of theexcitation light shining device 70 is not limited to the one which emitsthe light of the blue wavelength band. Thus, the excitation lightshining device 70 may adopt a laser diode which shines excitation lightof an ultraviolet range as the excitation light source 71.

In addition, the invention is not limited to the embodiment that hasbeen described above and can be modified variously in various stages incarrying out the invention without departing from the spirit and scopeof the invention. The functions which are executed in the aforesaidembodiment may be combined as in many ways as possible in carrying outthe invention. The aforesaid embodiment includes various steps, and bycombining appropriately the plurality of constituent requirementsdisclosed, various inventions can be extracted. For example, in theevent that the advantage can be obtained with some constituentrequirements deleted from all the constituent requirements disclosed inthe embodiment, the configuration in which the constituent requirementsare so deleted can be extracted as an invention.

1. A light source unit comprising: an excitation light shining devicefor emitting excitation light; a luminescent plate having a luminescentlight emitting area on a base material and adapted to emit a luminescentlight ray of a predetermined wavelength band by excitation light beingshone onto the luminescent light emitting area from the excitationshining device; two types of light source devices for emitting lightrays of wavelength bands which are different from that of theluminescent light ray emitted from the luminescent plate; a lightguiding optical system for guiding individually the luminescent lightray emitted from the luminescent plate and the light rays emitted fromthe two types of light sources to a predetermined plane; and a lightsource control device for controlling individually the emission of lightfrom the excitation light shining device and the two types of lightsources, wherein a synthetic light ray or a single-color light ray areemitted by controlling individually the emission of light from theexcitation light shining device and the two types of light sources bythe light source control device.
 2. A light source unit as set forth inclaim 1, wherein the luminescent plate is a luminescent wheel made up ofa base material which is driven to rotate by a wheel motor.
 3. A lightsource unit as set forth in claim 1, wherein a reflecting surface forreflecting light is formed on the luminescent light emitting area and aluminescent material layer for receiving the excitation light so as toemit a luminescent light ray is formed on the reflecting surface.
 4. Alight source unit as set forth in claim 1, wherein the excitation lightshining device comprises an excitation light source for emitting anexcitation light ray of a blue wavelength band, wherein the two types oflight source devices includes a red light source device having asemiconductor light emitting device for emitting a light ray of a redwavelength band and a blue light source device having a semiconductorlight emitting device for emitting a light ray of a blue wavelengthband, and wherein the luminescent light emitting area of the luminescentplate receives the excitation light from the excitation light shiningdevice so as to emit a light ray of a green wavelength band.
 5. A lightsource unit as set forth in claim 4, wherein the light source controldevice causes the excitation light shining device, the red light sourcedevice and the blue light source device to be turned on separately so asto include periods of time when light rays of green, red and bluewavelength bands are emitted separately and causes all the excitationlight shining device, the red light source device and the blue lightsource device to be turned on altogether so as to include a period oftime when a light ray of a white wavelength band is emitted which isgenerated by combining the light rays of green, red and blue wavelengthbands together.
 6. A light source unit as set forth in claim 4, whereinthe light source control device causes the excitation light shiningdevice, the red light source device and the blue light source device tobe turned on separately so as to include periods of time when light raysof green, red and blue wavelength bands are emitted separately andcauses the excitation light shining device and the red light sourcedevice to be turned on together so as to include a period of time when alight ray of a yellow wavelength band is emitted which is generated bycombining the light rays of green and red wavelength bands together. 7.A projector comprising the light source unit set forth in claim 1, adisplay device for generating an image by modulating light from thelight source unit, a light source-side optical system for guiding thelight ray from the light source unit to the display device, aprojection-side optical system for projecting an image emitted from thedisplay device onto a screen, and a projector control device forcontrolling the light source unit and the display device.